Used for the .30 Cal. Phantom LT/LTA Q.D. Sound Suppressor; Will NOT accommodate the 5.56 Phantom or Phantom M2 Sound Suppressors; Dual Support System supports and aligns the suppressor to your bore; 5-Port Design decreases visible flash; External Locking Mechanism keeps heat away from the spring mechanism; High-Temperature Spring holds up better over a longer service life; Threaded 1/2"-28